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Visual FoxPro

PDF Signature Appearance Width and Height

See more PDF Signatures Examples

This example explains how the width and height of the signature appearance rectangle box is determined.

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LOCAL lnSuccess
LOCAL loPdf
LOCAL loJson
LOCAL loJAppearance
LOCAL loCert

lnSuccess = 0

* This example requires the Chilkat API to have been previously unlocked.
* See Global Unlock Sample for sample code.

loPdf = CreateObject('Chilkat.Pdf')

* Load a PDF to be signed.
* The "hello.pdf" is available at https://chilkatsoft.com/hello.pdf
lnSuccess = loPdf.LoadFile("qa_data/pdf/hello.pdf")
IF (lnSuccess = 0) THEN
    ? loPdf.LastErrorText
    RELEASE loPdf
    CANCEL
ENDIF

* Options for signing are specified in JSON.
loJson = CreateObject('Chilkat.JsonObject')

* In most cases, the signingCertificateV2 and signingTime attributes are required.
loJson.UpdateInt("signingCertificateV2",1)
loJson.UpdateInt("signingTime",1)

* Put the signature on page 1, top left
loJson.UpdateInt("page",1)
loJson.UpdateString("appearance.y","top")
loJson.UpdateString("appearance.x","left")

* Add some text.
loJson.UpdateString("appearance.text[0]","Digitally signed by: cert_cn")
loJson.UpdateString("appearance.text[1]","current_dt")

* Add a built-in SVG graphic to the right.
loJson.UpdateString("appearance.image","blue-check-mark")
loJson.UpdateString("appearance.imagePlacement","right")
loJson.UpdateString("appearance.imageOpacity","100")

* There are 4 ways the width and height of the signature rectangle can be specified.
* 1) The width and height (in points) are both explicitly specified.
*    User space coordinates use "points" where 72 points equals 1 inch.
*    For example (3 inches wide and 1 inch high)
*    The fontScale is automatically chose to fit.  In addition, if a graphic (JPG or built-in SVG) is included,
*    it is automatically scaled such that the text + graphic fit together in the specified rectangle.
*    Note: When both height and width are explicitly specified, the resultant signature appearance rectangle
*    will match one of the dimensions, but the other dimension will be equal or smaller.  This is because the text
*    must be proportionally scaled.
loJson.UpdateInt("appearance.width",72 * 3)
loJson.UpdateInt("appearance.height",72)

* The signature would have this appearance. In this case, the height is actually less than 1 inch because
* if Chilkat chose a fontScale to fill the height, the resulting text's width would be too long for the desired width. 
* (image:https://example-code.com/images/explicit_width_height.jpg/endImage)

* 2) The width is explicitly specified, but we use the keyword "auto" for height.
*    In this case, the fontScale is chosen to achieve the desired width,
*    and the height will be whatever the result of the chosen font scale.
*    In this example, the width is 4 inches, and the height is "auto".
loJson.UpdateInt("appearance.width",72 * 4)
loJson.UpdateString("appearance.height","auto")

* The signature would have this appearance: 
* (image:https://example-code.com/images/explicit_width_auto_height.jpg/endImage)

* 3) The height is explicitly specified, but we use the keyword "auto" for width.
*    In this case, the fontScale is chosen to achieve the desired height,
*    and the width will be whatever the result of the chosen font scale.
*    In this example, the height is 1 inch (72 points) and the width is "auto".
loJson.UpdateString("appearance.width","auto")
loJson.UpdateInt("appearance.height",72)

* The signature would have this appearance.
* (image:https://example-code.com/images/explicit_height_auto_width.jpg/endImage)

* 4) Finally, we don't need to specify width/height at all.  Instead, we can choose a fontScale
*    and the dimensions of the PDF signature appearance's rectangle will be the result of using the
*    specified fontScale.

loJAppearance = CreateObject('Chilkat.JsonObject')
loJson.ObjectOf2("appearance",loJAppearance)

loJAppearance.Delete("width")
loJAppearance.Delete("height")
loJson.UpdateString("appearance.fontScale","10.0")

* With fontScale = "10.0"
* (image:https://example-code.com/images/font_scale_10.jpg/endImage)

* Load the signing certificate. (Use your own certificate.)
loCert = CreateObject('Chilkat.Cert')
lnSuccess = loCert.LoadPfxFile("qa_data/pfx/myPdfSigningCert.pfx","pfx_password")
IF (lnSuccess = 0) THEN
    ? loCert.LastErrorText
    RELEASE loPdf
    RELEASE loJson
    RELEASE loJAppearance
    RELEASE loCert
    CANCEL
ENDIF

* Tell the pdf object to use the certificate for signing.
lnSuccess = loPdf.SetSigningCert(loCert)
IF (lnSuccess = 0) THEN
    ? loPdf.LastErrorText
    RELEASE loPdf
    RELEASE loJson
    RELEASE loJAppearance
    RELEASE loCert
    CANCEL
ENDIF

lnSuccess = loPdf.SignPdf(loJson,"qa_output/hello_signed.pdf")
IF (lnSuccess = 0) THEN
    ? loPdf.LastErrorText
    RELEASE loPdf
    RELEASE loJson
    RELEASE loJAppearance
    RELEASE loCert
    CANCEL
ENDIF

? "The PDF has been successfully cryptographically signed."

RELEASE loPdf
RELEASE loJson
RELEASE loJAppearance
RELEASE loCert